Over the last decade, antibody-drug conjugates (ADCs) have emerged as a highly promising new class of biopharmaceuticals. By taking advantage of the specificity of monoclonal antibodies and the potency of small-molecule chemotherapy drugs, ADCs have proven to provide a highly effective combination – particularly in the oncology space,. The recent FDA approvals of Kadcyla (Genentech), Adcetris (Seattle Genetics), Mylotarg (Wyeth Holdings / Pfizer), and Besponsa (Wyeth Holdings / Pfizer), as well as the over sixty other ADCs in clinical trials, show that these drugs represent an increasing proportion of newly approved cancer therapies and will generate growing revenues for firms innovating in the field. Accompanying this burst in ADC development is the corresponding activity in the patent space. This article summarizes some of the important developments.